Electric fuse



Sept. 20, 1932. A. H. TRUMBULL ET AL 158478304 ELECTRIC FUSE Filed May28. 1928 Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE ALEXANDERH. TEUMBULL, OF STBATFORD, CONNECTICUT, AND GEORGE E. TRUM- IBULL, OFMANCHESTER DEPOT, VERMONT, ASSIGNORS, BY DIRECT AND MESNE AS- SIGNMENTS,TO THE BULLS-EYE ELECTRIC MANUFACTURING COMPANY, OF TOR- RINGTON,CONNECTICUT, A CORPORATION OF CONNECTICUT ELECTRIC FUSE Applicationflied May 28, 1928. Serial No. 281,086.

The present invention relates to electric fuses for use in electricinstallations, more particularly to fuse plugs, and has for one of itsobjects to provide a fuse plug of novel and improved construction wherebthe same is simplified and the visibility of t e interior of the plug isconsiderably enhanced and the amperage rating easily read.

A further object is to so construct the plug that, if desired, partsthereof may be renewed when worn and the insulation of the conductiveparts may be improved.

Further objects and advantages will appear from the followingSpecification and will be incorporated in the appended claims.

In the drawing which constitutes a part of the specification,

Fig. 1 is a longitudinal section through a plug made in accordance withthe principles of my invention showing the arrangement of the variousparts relative to each other;

Fig. 2 is a plan view looking down on the top of the plug;

Fig. 3 is a bottom plan view of the plug;

Fig. 4 is a View showing the base of the plug with the conductiveelements imbedded therein, and the connection of the fusible strip tothe conductors; all other parts of the plug being omitted for clarity ofillustration;

Fig. 5 shows a modified form of the arrangement of the conductor in thebase, the fusible element being integral with the conductors;

Figs. 6, 7 and 8 illustrate still further methods of connecting thefusible strip to the conductors.

The plug as illustrated in Figs. 1, 2, 3 and 4 comprises a chamberedbody member 10 molded or otherwise formed of insulating material of atranslucent or transparent nature, preferably of clear glass andprovided at its top with a peripheral flange 11 which may be milled asat 12 over portions of the edge thereof and at diametrically oppositesides of the cap in order to facilitate turning of the plug. A lens 13may be formed centrally of the top of the member and in alignment withthe chamber 14 formed in the body. Extending downwardly from the flange11 are the tubular side Walls 15 defining the chamber 14. If

the plug is to be of the screw type, the side walls 15 will beexteriorly threaded as shown at 16 to accommodate the thread 17 of ashell 18 for connecting the said parts together. If other types of plugsare used such as those employing bayonet slots and the like, it isobvious that the walls 15 may be shaped as required.

The shell 18 is of conductive material as copper or brass and isprovided at its lower end with an inturned circumferential flange 19which overlaps the flanged edge, to be hereinafter described, of acircular disclike base member 20 to hold it in place against the loweredge of the wall 15, the said base forming a closure for the chamber 14.The base 20 may be provided with ventilating openings or notches 20a topermit the escape of gases, etc.

The base member 20 is formed of insulating material as bakelite or thelike that is suitable for the imbedding therein of the conductor members21 and 22. The base member may be centrally domed outwardly as at 23providing the circumferential flange 23a referred to above provided onits upper face with upstanding lugs 24, portions 24a of which areadapted to fit snugly in recesses 24?) formed in the wall 15 of thechambered member 10 for centering the base relative to said member andto prevent relative rotation of these parts when the shell 18 is inplace.

Conductors 21 and 22 may be L-shaped and extend through the base atopposite sides thereof, the horizontal portion of the conductor 21 lyingpartly in a recess 25 in the dome 23 and extending laterally therefromto contact with the flange 19 of the shell 18 and lie between saidflange and the flange 23a of said base 20. The horizontal portion of theconductor 22 extends to a point centrally of the dome and constitutesthe contact for one of the contacts of the circuit.

The contacts 21 and 22 are connected within the chamber 14 by a fusiblestrip 26 of any weil known character which may be se-- cured toconductors 21 and 22 in some suitable way preferably by rivets 2'2." ormay be secured thereto in the manner shown in. Figs. 6, 7 and 8, inwhich case the fusible strip is apertured as at 28 to receivetherethrough lugs 29 on the ends of the conductors, these lugs beingbent over or peened down to secure the parts together or they may besplit as shown at 29a in Fig. 7 and bent over to hold the strip inplace. In the method of securing the fusible strip to the conductorsshown in Fig. 8, the conductors are provided .with outwardly flared ends35 which are extended through the apertures 28 and the resilence of theconductors 21 and 22 is depended upon to hold the parts together.Contact between conductor 21 and shell 18 is assured by a drop of solder30 placed thereon so as to bridge the two members.

It will be noted that the drop of solder lies partly in the recess 25thereby assisting in preventing turning action of the shell relative tothe base. At the same time the lugs 24, projecting into recesses 24aprevent relative rotation of the base and the wall 15. It will be seentherefore that the single drop of solder placed as stated above willprevent the removal of the shell an'd'base and consequently will preventaccess to the interior of the plug. This drop of solder may be readilyscraped off when it is desired to remove the shell from the chamberedmember for any purpose.

From the foregoing description it will appear that we have provided afuse plug to be used in electric circuits which is simple ofconstruction and cheap of manufacture, in which the insulation is highlyefiicient and in which when the fusible parts are burnt out, may bereadily disassembled andthe'burnt out parts renewed. We have alsoprovided aflug, the chambered part of which is molde of glass or othertransparent material andj provi ed with a lens in alignment with thechamber so that the condition of the fusible strip and other partswithin the interior of the chamber may be readily observed, the partsbeing enlarged and rendered therefore more visible. We have located theam rage notation or rating as at B on the usible strip so that whilecomparativel small, it ma be rea 'lyobserved through the lens ancorrectly read. We have simplified and chea ned the cost of manufacture,while providing a device of superior qualities and greater usefulness.

Having described our invention what we claim is:

1. A fuse plug for use in electric circuits, comprising a chambered bodyhaving a chamber defining exteriorally threaded tubular wall, aninsulating base member, contact members embedded therein, a shellthreaded to said wall, one of said contact members contacting with saidshell beneath said base, both contacts extending into the chamber and ahighly fusible member connecting said contacts within the chamber, 68said wall having recesses therein, said base having diametrically oposed lugs fitting said recesses, and a drop of solder connecting saidshell with the contacting contact member and preventing rotation of theshell.

2. A fuse plug comprising a body having an exteriorally threaded tubularwall defining a chamber, a base member constituting a closure for saidchamber, conductors extending therefrom into said chamber and fusiblyconnected therein, said wall having opposed recesses, lugs rising abovethe base and received in said recesses to prevent relative rotation ofthe base, a shell threaded to the wall and having a flange underlyingthe edge oft'he base and electrically connected with one of theconductors, a drop of solder conneoting the flange of shell with saidlast named conductor and holding the shell fixed relatively to saidbody.

3. A fuse plug comprising a one-piece molded body including a hollowtubular portion defining a chamber, a base constituting a closure forsaid chamber, contact members arranged within the chamber and havingangularly disposed extremities located beneath the base, a fusiblemember arranged within the chamber and connecting the contact members, ashell threaded on said tubu lar portion of the body and having aninwardly directed flange supporting said base, the offset extremity ofone of said contact members lying between the base and said flange andelectrically connected with the latter, and a drop of solder connectingthe said flange and contact member and holding the shell fixedrelatively to said body.

4. A fuse plug comprising a one-piece body including a hollow tubularportion havfiipg a chamber and spaced recesses and a magnifying lensportion integral with the bo y and disposed in a line with said chamber,a peripheral flange integrally formed on said body and having a handgripping portion around its edge, an insulating base constituting a'closure for said chamber, upstanding lugs on said base adapted tocooperate with the recesses in the tubular portion for centering thebase, contact members supported by sa1d base, each of said contactsextending below the base and one of 11 said contacts being formed withan offset foot portion, a fusible member arranged within the chamber andconnecting the contact members, a shell secured on said tubular portionand having an inwardly directed flange adapted to engage the offsetportion of the contact and means for making said engagement permanentwhereby said shell is fixedly held relative to the body portion.

5. A fuse plug comprising a one-piece glass 1 body having a magnif inglens portion at its outer end and a tubu ar portion extending therefrom,saidtubular portion having lateral projections for interlocking with ascrew shell, an insulating base -having prbjecting 13ostem and providedwith indicating characters visible through the lens portion, a screwshell interlocked -.with the lateral projections on the tubular portionand having a flange embracing the edge of the base, and electricalconducting means connecting the fuse strip to the screw shell,said meansincluding solder and preventing rotation of the screw shell with respectto thebase.

6. A fuse plug comprising a one-piece glass body closed at its outer endand having a hand grip portion and having a rearwardly projectingtubular portion provided with screw threads, an insulating base having aprojection and the tubular portion having a portion coacting with saidprojection to prevent rotation of the base with respect to the body, a.center contact member having a stem pro ecting through the base into thetubular portion, a side contact having a foot at the edge of the baseand a stem projecting into said tubular portion, a fuse strip connectingthe inner ends of said stems, a screw shell threaded on the tubularportion and having a flange embracing the edge of said base and solderconnecting a part of the screw shell to the foot of the side contact.

7. A fuse plug comprising a one-pieceglass body having a tubular portionwith an inner chamber and having threads on the exterior at the innerend and provided with a laterally projecting flange around the outer endconstituting ahand grip and having an outwardly projecting magnifyinglens portion in line with the inner chamber, an insulating base closingthe end of the chamber opposite the lens portion, said base and thetubular portion of the body'having interlocking portions preventingrelative rotation of the base and body, a screw shell mounted upon thethreads of the body and having a flange overlying the edge of the baseto hold the parts together, a center contact carried by the base, aconducting strip having one end interlocked with the base and secured toa part of the screw shell so as to prevent relative rotation of thescrew shell and base and a fuse member electrically connected to thecenter contact and to the screw shell and visible through the lensportion of the body.

In testimony whereof we aflix our signatures.

ALEXANDER H. TRUMBULL. GEORGE RTRUMBULL.

